copper operation, the crowding was increased by 64%, froth carry rate (t/m²h) by 75%, whereas the froth depth (mm) by 17%. Overall, this retrofit leads to improved process performance, making it a valuable addition to flotation cells equipped with center launders (Bermudez et al. 2024). By reducing froth transport distance and surface area of the cell by an average of 30%, the spider crowder upgrade significantly enhances froth crowding towards the launder, making it valuable for operations with low crowding. Since froth carry rate measures the effectiveness of the froth zone by indicating the proportion of particles being able to be collected as a concentrate (Corona-Arroyo et al. 2021), the substantial increase in froth carry rate positively affects the gained copper recovery. Additionally, the notable increase in froth depth of 17% can be seen to further improve concentrate quality by enhancing froth stability and facilitating the drainage of undesirable material back to the collection zone (Farrokhpay 2011; Bermudez et al. 2022). 5. CONCLUSIONS Effective froth management is crucial to achieving the optimized froth collection. By optimizing the froth surface parameters, the loss of valuable minerals to tailings can be minimized. The increased need for copper has been driving us to use even larger flotation cells. Together with increasing cell sizes and declining head grades, the need for optimal froth management has further increased due to the larger froth surface areas, longer froth transport distances, and coarser grind size of the flotation circuit. To address these challenges, different launder arrangements have been implemented, from which the center launder has proved to be the most efficient based on the several case studies presented. Key sites examined in this paper include the Bagdad Copper and Molybdenum Concentrator, Hudbay Constancia, Kennecott Copperton Concentrator, and Red Chris Concentrator. These case studies have shown that the implementation of center launder upgrades has proven highly efficient in improving operational parameters and the recovery of valuable minerals. The retrofits consistently decreased froth surface area and froth transport distance, while significantly increasing the recovery of copper and molybdenum. The recovery of copper improved very consistently under similar operating conditions across the different installations. The most substantial increase was observed in the recovery of coarser particles, with particles larger than 300 microns showing a recovery increase of copper over 16%. The studied upgrades led to significant improvements in froth mobility and operational flexibility, notably reducing the operational air flow rates and increasing the froth bed thickness. For example, at Kennecott Copperton, air flow rates were reduced by an average of 26% in the upgraded cells. Similarly, at Red Chris mine, air flow rates decreased by around 25%, enhancing flotation performance. The increase in froth bed thickness helped restrain the recovery of undesirable materials and improved froth stability, leading to better overall recovery. These upgrades also potentially contributed to energy savings and reduced CO₂ emissions, supporting decarbonization in flotation operations. According to payback period calculations for the studied retrofits, the investment payback period is estimated to be only a few months at the copper prices during the studied periods. Based on the literature, the price of copper is expected to remain high in the future due to declining ore
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